


Fading Light

by WhatTheDog



Category: Fate/Grand Order, Fate/stay night & Related Fandoms
Genre: Abuse, Character Study, Domestic Violence, Dubious Consent, Kind of angsty, M/M, Rough Sex, Sort Of, crackship, i wanted to take it serious though, put the warning just to be safe up there because it's pretty gray
Language: English
Status: Completed
Published: 2019-01-26
Updated: 2019-01-26
Packaged: 2019-10-16 11:05:09
Rating: Mature
Warnings: Rape/Non-Con
Chapters: 1
Words: 8,416
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/17548487
Author URL: https://archiveofourown.org/users/WhatTheDog/pseuds/WhatTheDog
Summary: In the wake of a shooting star, the young Cú Chulainn once made a wish. For Alter, it never came true. Born from corruption and designed for bloodshed, he shoulders his purpose without resentment. Monsters do not question their nature. He accepted this long ago.He did not anticipate the day Diarmuid ua Duibhne would tumble into his life and refuse to leave.





	Fading Light

**Author's Note:**

> Well, I wasn't planning on posting this originally, but after the positive response "Four Kisses from Cú" received I decided why the heck not. Fair warning: this fic is basically the polar opposite of that one tonally. I actually wrote this one first, wondered what was wrong with me, then hammered out "Four Kisses" in like two days because I needed something cute. 
> 
> This story takes place after E. Pluribus Unum obviously, and also after Diarmuid's interlude. I wasn't aware that Chaldea was located in Antarctica when I wrote this, so guess what, it's an AU where it's in Japan or some place like that. I don't know, the setting isn't important, it's just definitely not in Antarctica. 
> 
> Anyway, guess I've made it my mission to make the crack pairing of Diarmuid/Cú Alter a legitimate thing. Not sure if that's a good legacy, but whatever.

It is hot.

The heat invades his thoughts. It overwhelms, swallows him in its sticky embrace. For a moment, Alter wishes his outfit did not contain so much black.

But only for a moment. It is pointless to wish or to muse other possibilities.

Instead, he surveys the gathering. Some Chaldea event, required to attend, celebrating a recent victory. Wasn’t victory celebration enough? Apparently not to them. He would not be here given the choice.

The mood of the event is jovial. Servants flit among themselves, happy chatter wafting all the way to Alter’s position, exclamations of praise and friendship. He does not wish to partake.

Fortunately, no one objects. A small smile graces his lips at every uneasy glance or sidelong gaze. He makes them uncomfortable, and it shows. Who could blame them? He stands over a head taller than most, black and red and covered in spines, his parasitic tail twitching to some unseen stimulus. Only a fool would approach.

Unfortunately, fools abound. A shadow blocks out the sun’s merciless rays, and Alter is almost thankful for the temporary relief.

Almost.

“My Lord!” a voice cries. “How good to see you again. Would you like a refreshment? It is quite hot, is it not?”

He glowers at the source. A dark-haired man, stereotypically handsome, clad in green and misguided optimism. He is not short, but he does not even reach Alter’s shoulder. Familiar for some reason. Where has he seen him before?

“Well, I’ll grab that drink,” the man answers for him. He does not seem to be perturbed by the lack of response. “Be right back.”

He runs off, and Alter grunts in exasperation. Company. This was not in his plans.

When the man returns, he holds out a perspiring bottle, a grin lighting up his radiant features. Alter eyes it warily before accepting. The cold is a shock after the unending heat, but the change is welcome, the contrast almost soothing.

The man mops sweat from his brow. “Wow, that sun is unrelenting. Makes one wish for Ireland, huh?” He grins once more, perfect teeth practically glowing. “Mind asking your father if he can hold off for a bit?”

The mention of his father makes Alter tense. He is about to retort when the realization of the man’s identity hits him. Diarmuid! Yes, one of the Celtic warriors who served under him in America. Unimpressive, but loyal. Often to a fault, if he remembered correctly.

He regards Diarmuid once more, scrutinizing him. Not much has changed since America from what he can tell. Only his choice of attire. He is glad Diarmuid’s chest is now covered.

“Is something wrong, My Lord?” Diarmuid prompts. Perhaps he is uncomfortable.

Alter hopes he is.

“You know,” he starts, drawing out the syllable of the second word, “that we lost. I am no longer king.”

“I am aware. However, I am sure you know that a king and a lord are quite different.”

Hurm. He doesn’t know what to make of the response. The tone is lighthearted, effortlessly charming, accompanied by yet another one of Diarmuid’s dazzling smiles. A smile he might have had too, had he been anything other than what he is now.

“I suppose.” He takes a sip of the beverage. “Although such deference is no longer owed to me. You have the same Master as me now.”

Diarmuid nods. “Indeed. But a knight is loyal above all else. You may not hold authority over me in the eyes of Chaldea, but you are my lord, nonetheless.”

How peculiar. His allegiance did not end with defeat. Much like himself. He had still fought for Medb, even after her passing. As long as her cause remained alive, he was bound to carry it out.

But that cause was dead, thank Lugh. His allegiance had died as well.

Alter raises an eyebrow. “And what of Medb? Was she not your queen?”

Finally, a flash of discomfort. He basks in it.

“Well,” Diarmuid shifts, “yes. But,” like clockwork, that damn smile is back, “she is not here. Only you.”

Calculated. Apparently, he embraces Medb’s absence as well. However, his sentiments are foolish. Alter has no favor to give him—not that he would give it if he did. They are servants, and their sole purpose is to serve. To fight and die for their new Master. Not to entertain frivolous ideals.

“So loyalty prompts you to interrupt my peace?” He meets Diarmuid’s amber eyes, stares into their depths with an unblinking gaze. He is disappointed when the other man doesn’t avert his own.

“I apologize. I only wished to provide you some respite from the heat.” Diarmuid bows, somehow still smiling, posture giving no hint of disconcertion. “I will leave if that is your wish, My Lord.”

“Take your best guess.”

With one last cheerful grin, Diarmuid saunters away, bafflingly unoffended. Alter watches him go before analyzing his bottle.

He throws it away. He isn’t that thirsty, anyway.

* * *

A week later, another event is held. This time at dusk. A meet-and-greet, for the new servants Master has summoned.

Like before, Alter is required to attend.

He ignores the partygoers. A few brave souls attempt to make conversation, but his silence leaves them scrambling for an excuse to go.

He watches the fireflies instead. Intermittent light. Glow, then fade away. How appropriate to him.

“I see you are admiring the fireflies as well, My Lord.”

Alter wants to sigh at Diarmuid’s observation. Does this man not understand his solitude is on purpose?

“You know,” Diarmuid continues, blissfully unaware of the glare aimed in his direction, “some people call them lightning bugs. I’m not sure which term I prefer. Firefly makes me think of a soft glow, but then again, some of them do seem to light up suddenly and then disappear.” He laughs. “Just like lightning. I guess it’s all a matter of perspective.”

He smiles at Alter. “What term do you prefer?”

“I have never given it much thought.” Alter doesn’t break his glare.

Diarmuid still doesn’t seem to notice, or has chosen not to care. “I’ve heard the females don’t actually fly. That only the males are the ones we see hovering like this. Isn’t that something? All the females have to do is glow, and the males come flocking.” He shakes his head. “Maybe they’re more similar to us than at first glance.”

Alter has never wished to be another servant, but at this moment he longs to be Gorgon, only if to turn Diarmuid to stone with his stare. What is so damn interesting about some stupid bugs, anyway?

After several more minutes of chatter, he finally interrupts. “Are you woefully obtuse, or just inconsiderate?”

Diarmuid beams. “Neither. But if you  _truly_  hated my presence, I assumed you would have spoken up by now.”

Bastard. Is this what he was to expect from a subject?

The thought catches him off guard. Diarmuid is not his subject. He is just a deluded servant, carrying out some strange obligation only he understands.

He folds his arms. “What makes you think you are even worthy of a few words from me?”

“Nothing.” That insufferable, beautiful grin hasn’t wavered in the slightest. An errant lock rests across Diarmuid’s face, dark in contrast to the glimmer in his eyes. “And yet, you speak to me anyway.”

He should have killed him. Right there. Drawn Gáe Bolg and ended him where he stood. He could have easily explained it to Master. No one would have questioned him. No one _wanted_ to question him.

But he doesn’t. To his astonishment, a swell of amusement surfaces in his chest. The emotion feels alien in a situation other than battle. When had he last felt it when not in the throes of bloodlust? Never?

He chuckles. “You are a stupid and foolish man.”

Diarmuid laughs as well. “So I’ve been told.”

His presence is not any more pleasurable after the fleeting mirth, but Alter tolerates it better. He lets Diarmuid ramble on about the party, and their Master, and even a few stories about Ireland. The already scant light grows dimmer and dimmer until they are plunged into the embrace of night.

Diarmuid yawns. “Well, shall we? It seems like the party is about to end, anyway.”

Alter nods and turns away without another word. To his annoyance, Diarmuid falls into step beside him.

“Are the SSR dwellings nice? I think our accommodations are all right, but I’ve often wondered if the more valued servants get a better deal.” He smiles hopefully. “Could I see?”

With a grunt, Alter beckons him to follow. He has a feeling Diarmuid would have tried again another day had he declined.

Diarmuid keeps up his stream of consciousness throughout the entire walk. A headache starts to come on, and Alter can’t help his relief when his quarters come into view. He will make Diarmuid leave after this. He swears to it.

When they enter, Diarmuid spends close to a minute admiring the interior. “Not bad!” he finally says. “A little sparsely decorated, but that’s easy to fix.” Again, he flashes that radiant smile on his disgustingly handsome face. “If she were here, I bet Emer would know just what to do.”

From the widening eyes, Alter can tell Diarmuid has realized his mistake. It’s too late to backpedal, though. Every muscle has gone rigid, and an urge to throttle Diarmuid’s perfect neck nearly consumes him. How _dare_ he. How dare he mention her, dirty her name, even suggest she would have accepted a monster as her husband.

By some miracle, he doesn’t move from his spot. Through clenched teeth, he forces out, “Why are you here?”

Diarmuid’s smile is gone. He doesn’t meet Alter’s gaze. “I already told you. I wanted to see what the SSR accommodations are like.”

“No.” Alter takes a step closer, looming over Diarmuid now. “That’s not what I meant. Why are you  _here?_  Why did you talk to me? Why did you approach me in the first place?”

This time, Diarmuid does raise his head. Those amber eyes glint with an emotion Alter cannot discern. “Because I relate to you.”

“How,” he is practically spitting now, “could you possibly relate to  _me?_ ”

“Because I know how it feels to be taken by someone who’s obsessed with the idea of you.” Diarmuid swallows. His lower lip trembles, but his voice is steady. “Because I know how it feels to be forced into a role you never wanted to play.”

There is no hint of derision, of irony. Diarmuid is dead serious. Alter doesn’t know whether to laugh or hit him.

Instead, he takes in the strangely delicate features of the man before him: raven hair with a stubborn lock that refuses to stay in its place, falling to rest on the bridge of his nose. Full lips and high cheekbones that a strong jaw offsets. Well-defined arms from his twin spears, but supported by legs that are long and graceful. Diarmuid is every bit as beautiful as his legends claim.

He hates every damn inch of him.

“Take off your clothes.”

The words escape before he can stop himself, and there is a small spark of satisfaction at the surprise on Diarmuid’s face. For once, he is speechless.

“I said,” Alter growls, “take off your clothes. Or I will remove them for you.”

Diarmuid nods hurriedly, nimble fingers working to extricate himself from the offending garments. When he is done, Alter regards him again.

He is not a small man, in any sense of the word, but Alter dwarfs him in every respect. Amber eyes remain impassive as Alter drinks him in, as if this moment is predestined.

Without a sound, he grips those luscious locks and turns Diarmuid around, bending him over the table. If this maneuver is unexpected, Diarmuid does not let on, instead leaning forward, even widening his stance to allow better access.

The next few minutes are nothing but carnal. Alter grunts and thrusts, roughly digging the claws of one hand into Diarmuid’s side while the other grips his hair. He does not care about his conquest’s pain or pleasure, and though Diarmuid yelps a few times, he does not object.

When Alter returns to reality from his frenzied high, he realizes the state of the room. Several chairs lay upended or broken from his tail’s thrashing, and droplets of blood speckle the floor. He has to stop himself from laughing. Medb had always criticized him for not acting more “like an animal.” If only she could see him now.

The creak of his table brings his attention back to Diarmuid. The man is flushed, out of breath, the color in his cheeks matching several cuts decorating his torso and back. He turns around, and this time Alter is the one to avert his gaze. He does not wish to see whatever is in those amber eyes.

His own chest, much larger than Diarmuid’s, heaves as he pants. “Put on your clothes, then leave.”

It’s the only thing he can say right now. He busies himself with gathering up the scattered chairs while Diarmuid carries out the first part of his order. When finished, he bows, then leaves with a hushed “ _My Lord_.”

Alter stares at the table for an interminable minute. He produces Gáe Bolg without it ever leaving his sight.

In less than a blink of an eye, it is split into two.

* * *

There is some comfort in knowing Diarmuid will not return. Not after that. How could he?

Alter accompanies Master on a mission, who greets him cheerfully, yet reverently. If she had known what transpired the day before, she might not have been so courteous.

It isn’t surprising that she doesn’t know. He is the most feared servant in her possession. Had he been another, Diarmuid would have told without hesitation, and retribution would have been swift and merciless.

He is not another. He is the former Mad King, Tyrant of America.

After a few brief battles, victory is acquired without much exertion. Master congratulates them all, but especially him, of course. He carries the team on most missions.

He immediately separates from them when they reach Chaldea. It is cooler than it was a week ago, but the humidity has not abated. Shade is his only friend.

With a trunk of a tree to his back, Alter watches the other servants. Very few meet his gaze, but they lower their voices as they pass him by, as if he cares what nonsense they babble on about. Even the other Cús avoid him. He does not blame them, but a part of him wants to sneer:

“ _Do you see me? I am the You that could have been, the You that was never meant to exist but does. I am the You born from a Cursed Wish. I am the deepest part of your Id fully realized. I am a monster, but I am still You._ ”

It takes a second, but he realizes the passersby’s stares have been redirected to an approaching figure. A figure that now sits, directly next to him, with a smile as cheerful as the sunny day.

“I heard the news, My Lord. You were victorious yet again.”

He doesn’t know how to respond. There is not a trace of malice or even trepidation in Diarmuid’s voice. He looks for all the world like an excited puppy.

“I heard,” Diarmuid says, bouncing one leg, “that the other servants didn’t even have time to attack on the last skirmish. You took everything out. Is that true?”

“I suppose it is.” The words feel like they come from another. He is still flabbergasted at Diarmuid’s presence.

“Wow.” Leaning back, Diarmuid rests his hands in his lap. “Yet you don’t appear fatigued in the slightest. I suppose that’s how it is for us warriors, huh?”

Alter wants to snort. Diarmuid is not anywhere near his caliber. And there certainly isn’t an ‘us.’

“You appear well yourself,” he finally remarks. “I would have assumed after our last encounter you’d be desiring privacy.” His gaze bores down on Diarmuid. Though he does not ask a question, his stare demands answers.

Diarmuid nods, unperturbed. “Ah, yes. Well, I suppose for some that would be the course of action. However, I’ve never let a few thorns deter me.”

He winks, and Alter clenches his jaw. Is this mockery? Does he want to die?

“Have you eaten?” Diarmuid asks. He sits up. “I have not, and I was going to make lunch. You’re welcome to join me.”

Again, no hint of malice. Alter frowns, searching his face for hidden motivation. If present, Diarmuid betrays nothing, still smiling as radiantly as the first time they’d met in Chaldea.

He shrugs. “Fine.”

Though he does not eat, he accepts the offer. If anything, perhaps he can glean some insight as to Diarmuid’s intentions. The casual behavior offends him, seems out of place. What plan does this foolish knight have?

Before long, Diarmuid has invited him into the three-star quarters. It is not as roomy as his own domicile, but he’s not sure if that’s due to his status or his greater size. Even so, there are far more decorations here than at his own. Diarmuid holds some degree of popularity among the other servants, and gifts and keepsakes decorate the walls and shelves.

Alter examines a figurine, fashioned like a rose. It’s ornate, if gaudy, and rests on a special frame.

“Oh, that was a gift.” Diarmuid rushes to his side. “From the King of Knights.” He smiles faintly. “I will never forget our duel. It was an honor to face her in combat.”

Ah yes, the King of Knights—Artoria Saber. Alter cares little for her. She upholds ideals before purpose; probably why Diarmuid worships her. Why strive for honor and chivalry when they are nothing but tools?

“What would you like to eat?” Diarmuid moves away from the rose and sets several cuts of meat and produce onto a counter. “I went hunting recently, so most stuff is pretty fresh.”

He doesn’t care. Food is pointless. To eat is to survive, and his only purpose is to fight until death claims him.

After he selects his portion of the meat, Diarmuid cooks while maintaining a constant one-sided banter. Alter watches him dully until the food is ready. Does this man never shut up?

There is a wonderful, but short, period of silence when they both eat, and he uses it to analyze his lunch partner.

Diarmuid is neat. No morsels stain the edges of his mouth, and his napkin lays unused. Everything about him conveys a sense of relaxation, and irritation grows within Alter at each passing second. How could he be so calm? How could he ignore the elephant in the room? How could he even joke about it?

“Hope you enjoyed,” Diarmuid says after finishing, still obnoxiously cheerful and glowing. “I won’t keep you if you’d like to be on your way.”

“Perhaps I have business here.” Alter stands, increasing the already present height disparity between him and the still seated Diarmuid. “I’m still welcome here, am I not?”

“Sure.” Diarmuid is unfazed. “I did invite you over.”

“You did.” He moves closer, tapping his claws on the counter all the while, forcing Diarmuid to crane his neck. “You invited me in, even knowing there might be consequences. Surely, you must be aware of that. I refuse to believe even  _you_  would be stupid enough not to.”

The words are meant to bite, but Diarmuid betrays no signs of intimidation, only nodding solemnly. “I assumed, yes.” He smiles. “But as your knight, I must offer reparations for offenses, intentional or not. I made quite the blunder last time, and I hope this lunch has mended any damage I caused.”

He stands and bows. “My Lord.”

Alter has had enough. He grabs Diarmuid roughly. “What game are you playing?” he hisses, lowering his head so they are face to face.

Still, Diarmuid does not cower. “None. I invited you in for lunch. That is all.”

“Because you relate to me?” He laughs harshly. “How could I forget how much we have in common!”

“Maybe more than you think.” Diarmuid does not blink, and there is a strange look in his eyes. “Two stories don’t have to be identical for there to be parallels.”

“You are infuriating.”

It is the last thing Alter says before kissing him violently, ramming him against the wall.

Diarmuid does not fight him. He kisses back, places his hands on Alter’s chest, only for them to be shoved away.

“Don’t touch me!” Alter snarls. “If you must do something with your hands, then help me with these damn buckles you insist on wearing.”

When Diarmuid is appropriately disrobed, Alter grasps his backside, tilting him into position. He growls and ruts, crushing the smaller man into the wall in such a way that bruises are inevitable. It must hurt. He hopes it hurts.

He roars when finished, rattling the various keepsakes, driving Diarmuid into the wall one last time. He doubts it goes unnoticed. This area is not as secluded as the SSR dwellings.

Bracing one hand against the wall, he collects his thoughts. Diarmuid is still pressed against him. He glances down, takes in the disheveled hair and blossoming colonies of purple. A testimony to lust and violence. He can’t find any remorse or satisfaction in their existence. Signatures of battle; no more, no less.

Now on his feet, Diarmuid regards him with an almost curious expression. He isn’t sure what it means, nor does he care to find out.

He lowers his head, dragging his claws down the wall. “Well then.”

“Well then,” Diarmuid repeats. He stands on his toes, pressing their lips together.

Alter jerks back. He grabs Diarmuid’s face, making sure to dig into the skin. “What did I say?” He slams Diarmuid’s head into the wall. “Never touch me,” he says through bared teeth, “and never kiss me unless I do it first!”

Just because he can, he ends by capturing the other man’s mouth, biting on his lip with such force that copper overwhelms the taste. He pulls back, spitting Diarmuid’s blood into his face.

“Your _Lord_ hopes you remember this.”

Diarmuid still does not cry or whine or beg. He merely nods. “Of course, My Lord. My apologies.”

His apologies. Alter snorts. “Which part of this did you relate to?”

“All of it,” Diarmuid says, then cleans up without another word.

* * *

He does not understand Diarmuid ua Duibhne.

He does not want to.

Though it takes a couple days this time, Diarmuid seeks him out again, with a greeting of a bow and a cheerful “ _My Lord_.” He endures the babble, only responding on the rare occasion, and then departs to his quarters with Diarmuid trailing behind.

When the inevitable happens, Diarmuid only reacts with that near-curious expression. No fuss, no wails, no begging. He leaves with new cuts and bruises, yet his courtesy never wavers.

It becomes a routine. Sometimes in Alter’s quarters, sometimes Diarmuid’s.

Alter pins him down, biting and sucking and licking every inch, raking claws along his back. There is no desire, only primal urges, a strange fascination with defiling beauty. Isn’t that what Alter is? Defiled, corrupted, twisted. It’s not satisfying, pursuing cruelty for cruelty’s sake, but he can’t stop.

He never allows Diarmuid to initiate. Only he has that privilege, however, there is never any resistance. Diarmuid obeys every order, follows all directions, carries out any commands. He does not complain, regardless of how rough or unrelenting Alter gets. What is his breaking point? No matter what, Alter can’t seem to reach Diarmuid’s proverbial ‘uncle,’ and the nonexistent threshold is aggravating.

Another day, and again they engage in this bizarre ritual. Alter finishes with his last few strokes, clutching Diarmuid close to him, shuddering from the rush of endorphins. His sheets are torn and ripped, casualties of war. He doesn’t remember when it happened.

Neither does he remember when Diarmuid’s legs became wrapped around his waist. He untangles them, frowning. He won’t punish Diarmuid for it, even if it technically violates the ‘no touching’ rule. It made things easier for him.

When he leaves the bed to get dressed, Diarmuid sits up. Bite marks and hickeys cover his chest, but if they bother him, he does not voice his displeasure.

“Are you going with Master on the mission tomorrow, My Lord?”

Of course. Master takes him on most missions. Alter resists the urge to roll his eyes as he fixes his hood. “I believe so.”

“You are her favorite.” Diarmuid looks off wistfully. Is there a hint of envy in his voice?

Alter shakes his head. “That has nothing to do with it. I am good in a fight. That is all.”

“Perhaps,” Diarmuid says absentmindedly. “Though one would expect nothing less from Cú Chulainn.”

For some unknown reason the sound of his name makes him flinch. It’s not like others never refer to him by his actual identity. However, hearing it come from Diarmuid’s lips seems taboo.

His only reply is a grunt. He’s fully clothed now, so he busies himself with polishing his spear. Anything to ignore the figure on his bed.

“Are you looking forward to the fight?” Diarmuid asks.

Another question deliberately expecting an answer. For once, he misses the one-sided banter.

“No,” he responds truthfully. “It’s something that must be done. I look forward to it as much as my spear does.”

“Because you’re nothing more than a weapon?”

Diarmuid is smirking now, and distaste coats Alter’s mouth. Why does he care?

The smirk is gradually becoming more coy. “Or a tool for Master to use. Your own ambitions and passions forgotten for the sake of her goal. Am I right?”

Alter glares. “Get out.”

* * *

He's not sure why Diarmuid’s observation gets under his skin, but it does.

It’s not even a secret. He’s been quite transparent on his views. He’s not like his Lancer persona, who delights in the thrill of battle, whose only wish is that of a shooting star—shine for all to see before the light fades.

He has no wish. He is nothing but that faded light, smoldering and desolate. All he can do is wait to be fully extinguished.

After the mission, Alter avoids Diarmuid. Any time he sees the dark head of hair bobbing through a group of servants or a forest green streak rushing forward, he turns and strides away. He secludes himself in his quarters. Unless Master calls, he does not leave.

A week goes by, filled with nothing but missions and isolation. It’s not unpleasant, but it feels unnatural. Somehow he has gotten used to Diarmuid’s smiling presence.

It therefore comes as a shock that the next sighting Alter has of him, he is seated under a tree, a frown clouding that radiant countenance.

Curiosity gets the best of him. He approaches Diarmuid, the only time he has done it first. He stares down at his crestfallen subject. There is no acknowledgement of his presence, and annoyance replaces his former emotion.

He clears his throat.

Diarmuid still does not raise his head.

“For one known for their observational skills, you seem surprisingly oblivious,” Alter finally says. He folds his arms, awaiting the expected response of an apologetic “ _My Lord_.”

It doesn’t come. Instead, Diarmuid sighs, resting his cheek in his hand. The melancholic expression is almost amusing, but Alter can’t help but feel disgruntled. After all his attempts, he has never elicited this kind of reaction. What could have possibly done this?

With a sigh of his own, Alter takes a seat next to him. “What’s bothering you?

“Fionn has been summoned.”

Alter has to bite back a laugh. Out of all the reasons, it’s this? Really?

He composes himself. “What’s wrong with that?”

“Nothing.” Diarmuid droops further.

“You aren’t acting like it’s nothing.” Alter cocks his head. “I would have thought you’d be pleased that someone from your past life is here. And a former commander, to boot.”

“Are you aware of my legend?” Diarmuid asks. He still hasn’t looked over.

Alter shrugs. “Well enough.”

He has the gist of the story. Diarmuid ran away with Fionn’s betrothed, eventually receiving his blessing to marry after years of pursuit and exile. However, on a boar hunt, Diarmuid is fatally wounded, and Fionn leaves him to die. A typical tale of forbidden love. It’s never struck his interest.

“Then you must be aware of our history.”

“Yes.” Alter frowns. “However, I thought that was water under the bridge. You fought together in America. Fionn did not seem to hold any ill will toward you, even if he made a jab or two. There doesn’t seem to be residual resentment besides his failing to give you water. Even so, he did try to rectify it.”

Diarmuid sighs again. “It’s not the residual resentment on his side I’m worried about.”

Interesting. Alter can’t help but raise an eyebrow. So Diarmuid, pleasant to all under any circumstance, is capable of holding a grudge?

A chuckle worms its way out involuntarily, and Diarmuid finally glances his way.

“I suppose my moping is undignified.” He gives a slight bow. “Forgive my attitude, My Lord. I will try to do better.”

Alter stands and helps him to his feet. “Would you like a drink?”

A flicker of a smile flashes on Diarmuid’s face before he nods. “Yes, that… that sounds good.”

In Alter’s quarters, he fishes out an old bottle of whiskey. He doesn’t remember where it came from—possibly a token from some battle.

Diarmuid slams down a glass, then pours himself another.

Alter watches him, folding his arms. “You might want to slow down there. It’s not going to run away."

“I apologize, My Lord.”

“Will you stop that?”

The words come out harsher than he intended, and he sucks in a breath. “I meant... you don’t have to apologize for every tiny thing. I promise I won’t bite your head off.”

Why is he even explaining himself? It doesn’t matter what Diarmuid thinks of his tone. He finds himself frowning, mood growing sour. At least there’s a distraction present.

He might have promised not to bite Diarmuid’s head, but that doesn’t apply to the rest of him.

* * *

Back to the same old routine. A frenzy of heat and madness, always ending with broken skin and furniture. He’s practically memorized Diarmuid’s body at this point. Knows the sensitive areas, the best places to make his conquest squirm. Diarmuid is so receptive to all of his caresses, so willing to engage in any position.

They aren’t quiet in their escapades, and it’s obvious everyone knows of their involvement together.

No one voices objection to Alter. He never bothers to ask Diarmuid if he’s been lectured, but the stares and whispers whenever they sit together aren’t exactly surreptitious.

Even Master knows. She hasn’t treated him any differently, but he notices she mentions Diarmuid to him more often, as if she believes that will stimulate conversation.

It doesn’t. He has nothing to say on the matter. Diarmuid is just another servant.

True, other servants don’t dutifully get on their knees and service him. Other servants don’t endure his weight on top of them, grinding them into the mattress. Other servants don’t hug the wall as he bites their neck, aligning their hips together.

Officially, Diarmuid may no longer be his subject, but he still serves under him.

Their encounters play out like clockwork for several weeks. Aggravatingly, Diarmuid sometimes insists they partake in other less salacious activities, eagerly asking him his opinion the few times he agrees. There is always disappointment when he has nothing to comment.

He’d much rather desecrate the man. Take him to the brink and beyond, indulging in every twisted thought capable. It’s a regimen they’ve both come to expect. There’s nothing to suggest anything would get in the way.

Today, something did.

He has just completed a mission, a bit of a longer one, when he decides to head to the sparring area. It’s not a place he typically occupies. None of the other servants pose any kind of challenge, and it’s almost distressing watching a caster try to fight.

There is a hush when he arrives. He ignores it and sits on the sidelines, scanning the crowd that’s trying so hard not to stare. They must be wondering what he’s looking for.

They will have to keep wondering. He’ll never admit he’s trying to find dark hair and a green tunic.

After a minute, he purses his lips. Diarmuid frequents this area. It shouldn’t be this hard to find him.

Like so many times before, his attention is caught by that familiar cry of “ _My Lord_.” He turns as Diarmuid strolls over to him, but he frowns at the figure accompanying him.

Fionn.

“Diarmuid, what is this?” Fionn laughs jovially as Diarmuid flashes a strained smile. “Do you refer to everyone by that?”

“N-no.” Diarmuid blushes. Something Alter has not yet had the privilege to see. “Only—"

“Oh, I’m kidding. You don’t need to explain yourself.” Fionn regards Alter, grinning. “Though I am surprised you’d use the same title for both of us. Unless you’re trying to tell me something.” He winks at Diarmuid, who turns a furious shade of scarlet.

As Diarmuid stammers out a response, Alter levels a steely glare at Fionn. The _nerve_. Sure, he has no exclusive right to Diarmuid, but Fionn dares to be so flagrant right in front of him. It’s insulting in more ways than one.

Perhaps he’ll get lucky and Fionn will need a new sparring partner. Then, oops. He didn’t _mean_ to stab him.

But that scenario depends on luck. It’s usually easier to take matters into his own hands.

“So, Fionn,” Alter starts, trying to pronounce the words with as much distaste as possible, “you’re a lancer. How do you compare to the other Celtic lancers?”

The man puffs out his chest. “I’m one of the best.”

“Really?” Sarcasm drips from the word, and it’s gratifying to watch Fionn’s smile waver.

“Well… obviously not _the_ best. But… I’m up there.”

Alter stands up. “Could you take on a berserker who happens to use a spear?”

“Okay!” Diarmuid claps his hands together. “This has been just superb, but it’s getting late. I think we’re all a bit tired and stressed, you know?” His signature smile appears, still stunning in spite of being forced. “Glad everyone got to meet.” He gives a quick bow to Fionn. “It was a pleasure sparring with you. Until next time, My Lord.”

Fionn doesn’t take his eyes off of Alter. “Until next time.”

With the farewells over, Alter spins on his heel, marching off. Diarmuid follows close behind.

“Why do you call him ‘ _My Lord_ ’?” Alter asks when they are out of earshot.

“Because he is. I was his knight for a long time.”

Alter doesn’t slow his pace even though Diarmuid is struggling to keep up. “Does one of us rank above the other?”

“Well—”

“In a situation with conflicting orders, who would you choose to obey?”

Diarmuid sounds flustered. “I… that’s very dependent. I served you both at different times, and… in America we were both… but that’s over, so…”

“So you don’t have an answer.” He comes to an abrupt halt, and Diarmuid nearly collides into his back. “It doesn’t matter to you.”

“It does matter,” comes the quiet reply. “I just can’t give you the answer you want.”

What a cop-out. He clenches a fist, trying to ignore the fury pulsing in his temples. This isn’t like him, this reaction; he’s temperamental, yes, but possessive, never. Diarmuid’s allegiance is irrelevant. Who cares if he still bears loyalty to Fionn?

With a shake of his head, he resumes his stride. They’re in his quarters shortly after.

Like always, Diarmuid doesn’t protest when he guides him onto the bed. Straddling him, Alter nips and kisses Diarmuid’s exposed neck, traveling down to his collarbone. One hand works on removing the green tunic while another moves south to grip and stroke, drawing a muted gasp.

He peppers a few more kisses past Diarmuid’s collarbone, growing rougher with his teeth the further he goes. He stops his ministrations below to clutch that lustrous head of hair when Diarmuid whispers, “Did it bother you when you had to fight Scáthach?”

He stops. Freezes. Raising his head, he finds Diarmuid’s eyes shimmer with moisture.

“I mean,” Diarmuid’s stare is unfocused, “in America. Was it… hard? Do you… do you ever think about it?”

This is not the direction he intended for this encounter. What does this have to do with anything? Still, if humoring Diarmuid gets him results, he’ll do it.

“She was an enemy.” His voice is flat. “It had to be done.”

The harsh laugh catches him off guard.

“No, that’s not what I asked. Of course it had to be done if she opposed you.” Diarmuid faces him, expression unreadable. “I asked if it bothered you, to fight against your mentor. When you accompany Master on missions, does it ever gnaw on your subconscious? That you had no control, only the compulsion of a geas? Does it bother you that Scáthach chose to fight you instead of Medb?”

“I don’t dwell on those things.”

“Fine. Don’t answer.” Diarmuid twists away.

It is the first time he’s approached anything resembling disrespect. Almost like a petulant child.

Alter has no plans to let it slide.

He jerks Diarmuid back to face him. “My dear knight, I did answer you.  _I just can’t give you the answer you want_. You think we’re similar just because we both had a geas placed by a neurotic woman, but that’s the extent of it. I am not like you, and you are not like me. The sooner you appreciate that, the sooner you’ll stop being disappointed when I don’t turn out like you’ve imagined.”

Silence.

He leans closer. “Well? I’ve never gotten you to shut up before. Why now?”

“Did you want to do it?”

He flicks his tail. “Why are you asking me irrelevant—”

“Did you want to fight Scáthach?” Diarmuid purses his lips. “Was it satisfying for you?”

“Stop with this nonsense,” he growls. The end of his limit is drawing dangerously close.

Diarmuid doesn’t heed him. “Did you want to fight any of them? Nero or Rama or Karna—”

“No!” he snarls. “I didn’t! I didn’t want to fight them, but I also didn’t care when any of them died.” He bares his teeth. “Is that the answer you wanted? The one you hoped for? Because I won’t lie and say I stay awake at night, eaten by remorse over anything I did. I did what I was created to do, and that’s all that matters to me. I don’t care if it’s vile or horrible or whatnot. My entire existence is vile.”

Diarmuid nods, gaze faraway. “I thought you’d say that…”

Something snaps inside him. The limit is reached. He strikes Diarmuid across the cheek. Gripping one shoulder so forcefully the skin breaks, he shoves his face into Diarmuid’s, close enough that a few ragged breaths speckle him with saliva and blood. “What do you want out of this? What’s your purpose for coming here, again and again?”

“I’ve told you.” Diarmuid swallows noisily, but the moisture in his eyes is gone. “You don’t believe me, though.”

“No, I don’t.” Alter sits back. A smile slowly unfolds on his face. “You know what I think? Why you keep coming here?” He places both hands on Diarmuid’s chest, smile only growing wider. “I think you want just one superior of yours to find something worthwhile in you. Haven’t all of them found you disappointing? In one way or another? But I was okay with your failure in America. I didn’t punish you for it. It gave you hope, that maybe I’d be the first to actually be proud of you.”

Diarmuid’s face is impassive. Alter strokes it in a mocking imitation of concern.

“Do you really believe if you put up with everything, if you let me fuck you and hurt you and use you in every way that it would make me respect you? That if you never complained, I’d grow fond of you, hell, maybe even _love_ you.”

“No.” Diarmuid is trembling now.

“Are you sure?” He lowers his head as he tilts Diarmuid’s upward. “Absolutely positive?” He kisses him, forcing his tongue through closed lips, where it languidly rolls like the tide.

To his surprise, Diarmuid jerks away. “I don’t think that. I never thought that would happen, and I never wanted it to happen.”

Alter snorts. “Then what do you want?”

Diarmuid releases a shuddering breath. “For you to find out what you want.” He swallows again. “Not just a purpose. Not something you feel obligated to do.” His voice drops to a whisper. “I want you to figure out your wish.”

Alter wants to retort. He wants to hit him again. He wants to roll his eyes. He wants to scream. He wants to do a million things that all bounce and whirl inside of his mind at the same time. But one thought overwhelms them all:

_I don’t know what I want._

_And I’m so scared that no matter how hard I try…_

_It…_

_Will…_

_Always…_

_Be…_

_Nothing._

He has never cried. Not for as long as he can remember. He isn’t about to start now.

He gets up, releasing Diarmuid from underneath him. Moving away, he walks toward the far wall. Blank. No decorations. No memories. No keepsakes. Empty. He squeezes his eyes shut.

The entire time, Diarmuid does not say a word. When Alter turns around, he finds it is because he is alone.

* * *

For the first time ever, Alter fumbles in a battle.

It’s not a catastrophic error. It doesn’t cost them victory. But it is something that shouldn’t have happened. He should have been more aware. He should have fought better.

The small blunders start building up. He’s not doing as much damage as he normally would. His reaction time is off. Everything seems wrong somehow.

When the mission is over, Master tells him to take a break. A little time off should cure him.

It doesn’t. He’s stuck in a fog, a strange limbo. His spear feels unnatural in his hands. What is happening to him?

Master gives him more time off. He’s not sure why. It won’t fix anything. All he does is sit in his quarters, alone. No one comes to visit. No one.

Not even Diarmuid.

He’s never been lonely before. He’s never cared about attachments like the other servants. It was enough to fight. Not satisfying, but enough. He had no other reason for existing.

Now he can’t even do that.

He wants to hate Diarmuid. For cursing him like this, but he can’t bring himself. Like everything else, there’s no passion to it. It’s nothing but a hollow emotion.

He's as empty as his walls. A husk of a Heroic Spirit. Perhaps he’s not even smoldering light. Maybe he’s nothing but shadow. Absence. Devoid of the spark that made Cú Chulainn who he is.

In vain, he searches deep within, faces the defiled remnants of himself. There must be something. He must want something.

He always comes up empty-handed. Again and again. He knows the truth, but for once, it robs him of breath and drive.

He is not a person. He never was.

* * *

Even with his prolonged solitude, it’s not a surprise when Diarmuid does show up. He lets him in, but then ignores his presence. Only this time, it isn’t done out of irritation or spite. There’s none of that.

He simply can’t bring himself to care.

“Master sent me to talk to you,” comes Diarmuid’s voice.

He doesn’t look over.

“I figured you wanted to be alone, but she insisted.”

Footsteps approach him, and there’s a shift in the mattress as Diarmuid sits next to him.

“I’m assuming you haven’t had much luck in self-reflection?”

There is nothing to reflect on. He’s fundamentally broken, a thing that never should have existed.

Diarmuid lets out a sigh. “That’s okay. You don’t have to talk.” He chuckles. “I’m pretty good at carrying on conversations by myself. I’m sure you’ve noticed that.”

Normally, the glib tone would have bothered him. But it can’t pierce his cloud of apathy.

“I’m sorry about all of this. I really am. I… I didn’t intend for this to happen. I guess I just wanted…” Diarmuid laughs. “Maybe you were right. I got so caught up in my own experiences that I didn’t consider what was best for you. I just assumed you were like me. That you shoved everything inside, made your whole identify nothing more than a title.”

Alter finally looks over.

Diarmuid runs a hand through his dark locks. “If you don’t have a wish… that’s… that’s okay. You don’t need one.”

“What is your wish?”

It’s the first thing Alter has said, and Diarmuid jumps at the noise.

“Me?” He blinks, lowering his head. “My wish…” He sighs again. “I want to stop regretting my past. To actually move forward. I want… to help people. To be more than just a knight; not to atone for my transgressions, not to appease anyone, but for me. Because it’s the right thing to do. Chivalry is about protecting others, and I want to truly live it out. That’s what I want.”

Unsurprising. Many of the Heroic Spirits share this wish. It’s almost standard. But it doesn’t answer all of Alter’s questions.

“Why did you put up with me?” He stares Diarmuid down. “Why did you never tell me to stop?”

“I guess…” Diarmuid picks at a spot on the sheets, amber eyes downcast. “I thought it was best to let you use up all of your pent-up anger. I… maybe it was another instance of me projecting, but I’ve been there. Bottling everything up until it just explodes. I thought it was what you needed, and it… it did hurt. It took a lot for me to keep coming back. But I just kept telling myself if I were truly loyal, I’d stick by you for however long it took. That it was the price I had to pay to help you.”

This would have been heartbreaking if Alter had a heart to break. Instead, there’s just more emptiness.

“You can’t save me,” he says flatly.

Diarmuid nods. “Yes. I know. Of course I can’t.”

“Then why bother?”

“Well…” He smiles. “Just because I can’t save you, doesn’t mean no one can. I wanted to help you along the way.”

Alter snorts. “If you don’t believe you can do it, then who do you believe can?”

“You.” Diarmuid gently takes Alter’s hand. “Only you.”

Alter stares at the hand resting on his. So much smaller, with nails that are short and neat, unlike the cruel tips of his claws. The touch is soft, tender, and it makes his breath catch in his throat. How many times has he taken this man? Yet this moment is so intimate it overwhelms him.

He can’t bear it and withdraws his arm. “I’m a monster. Nothing in this world can change that.”

“Sure.” Diarmuid shifts. “You’re right. You are. But that doesn’t make you less deserving than anyone else.”

Nonsense. He frowns. “How can you say that after everything I’ve put you through?” Squaring his shoulders, he stares Diarmuid down once more. “Your commitment is commendable. But no matter what you do, how many layers you peel away, you’re not going to find anything worth salvaging. Medb made me with a specific vision in mind, and it wasn’t one that could be redeemed. All I am is a force to destroy and subjugate. Nothing more.”

“Well, there’s your biggest problem.” Diarmuid holds his stare, gaze harder than Alter has ever seen it. “I’m not trying to excuse you. Just because I understand the place where your feelings come from doesn’t mean I condone it.” He folds his arms. “Medb is not the problem. Well… okay, she’s not innocent. But the real issue is that you blame everything you do on her. Nothing is ever your fault.” He shakes his head. “If you’re irredeemable, it isn’t due to your nature, but because you use it as a crutch. You might be fearless in battle, but you’re a coward, through and through.”

There is an odd ringing in Alter’s ears as Diarmuid finishes. An echo of his words. His throat fills with the urge to tear off the man's handsome face. It scorches and burns. Fizzles. Dissipates.

Because above all, there is the bizarre horror that he has no retaliation. He can’t deny any of it.

Diarmuid suddenly hangs his head. “That… that was flippant of me. I apologize. I should not have been so direct.”

“There’s no need.” Even though the voice is his own, the words sound faraway. He still hasn’t recovered.

He doubts the other man has, either.

Diarmuid bows his head. “Thank you.” He stands up. Moves to face Alter. “Regardless of anything I said… I resolved to help, and I will not give up in spite of challenges.” Once more, he offers his hand. “Cú Chulainn, would you like to sit outside and watch the sunset?”

An eternity passes as he stares at the outstretched fingers. There is an ocean stretching between them. Seemingly impossible to cross.

Is  _he_  capable of crossing it?

He takes the hand. Lets Diarmuid help him to his feet. “I would,” he says, “but only on one condition.”

“Oh?”

He lets out a deep breath. This is the hardest order he’s ever had to give. “You will refuse to let anyone hurt you for the sake of loyalty. You will never do anything you don’t want to do.” He bows his head, lets the unfamiliar notion of selflessness consume him. “Not from anyone. Not even me.”

Diarmuid nods, that beautiful smile present, more radiant than the sun. The one Alter didn’t realize he missed so much. “Understood. I accept these terms.”

“Good,” Alter says. Then for once, he is the one to follow Diarmuid, where they watch streaks of purple and orange blaze across the horizon, the whole sky a mural.

Perhaps, he reasons, even fading light can have merits.

**Author's Note:**

> Thanks for reading!


End file.
